Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 51 users online :: 3 registered, 0 hidden and 48 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Directional Control Valves (3way valves and stuff like that)

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
Sponsored 
  • Author
    Message

Directional Control Valves (3way valves and stuff like that)

Unread postAuthor: POLAND_SPUD » Sun Mar 07, 2010 1:12 am

Directional Control Valves, commonly refereed to as 3,4,5 etc. valves or spool/poppet valves etc., can be very useful for spuders.
They can be used both in pneumatics (to fill/vent QEVs/piston valves) or in combustions (to build automated metering systems).

DCVs are not as complicated as they seem. However in order to use them effectively one has to understand some basic concepts underlying them. Understanding the symbols used to represent how they work is crucial.

I won't write about some basics as there are already some quite good sources of information on them. Though I'll write a bit about their utility from the point of view of a spudder, and which DCVs are the best in general and for particular applications


You'll find the most basic stuff in these links(not all of them are only about DCVs but I suggest reading everything anyway)

Introduction to pneumatics

Pneumatic notes (similar in scope to the first link, though it still might be a good idea to read it)

A book on pneumatics and hydraulics. Again, not everything is 100% relevant for spudders

Here you can find some animations of 2,3 and 4(5) way valves

more symbols

animated intro to DCVs (and pneumatics in general)

Now let's move on from the theory and symbols to how real valves are built. Generally speaking there are two types of valves: Poppet and spool valves

I think that this is best explained...
Here(pay attention to the part discussing valve actuation methods... this notion comes down to 'how do you want to operate the valve? by a push button / lever (with a spring return), a solenoid or maybe you want to pilot it with another valve... etc. )

and here
this site is really great, it has a lot info and links to useful stuff


If you are already familiar with all the info that can be found in links above let's discuss what valve would be the best for what application.

Generally speaking the biggest limitation is the pressure used. Most valves are designed to operate at about 10 - 15 bar pressure max
While this is enough for quite a lot of uses many spudders use higher pressures ( 20 - 50 bar) to get more power
Luckily, some valves can handle high pressures pretty good


Let's compare different valve as far as their ability to handle high pressure is concerned:

POPPET VS SPOOL valves
poppet valves are not balanced so as the pressure increase the fore needed to actuate them increases too.

DIRECT VS INDIRECT acting
indirect acting valves are piloted valves. Piloted valves have small inbuilt valves that pilot the main spool. However since those 'piloting' valves are generally not balanced - as a result they leak when used at higher pressures

To sum it up. The ideal valve for use with higher pressures is a direct acting spool valve


I'll update the rest later... Feel free to PM if you find something that can be posted here
  • 0

Attachments
QEV+3wayV.jpg
this pic shows how to use a 3 way valve to pilot a QEV. The pink boxes represent the flow through the valve:
the one to the right shows flow in normal position (air flows from the air source (not connected here) to the pilot side of a QEV

the box to the left shows how flow path changes when I 'switch' (by pulling the lever) the valve (air source is blocked off while the pilot side of the QEV is vented)
example_indirectact.jpg
Last edited by POLAND_SPUD on Sun May 23, 2010 6:24 pm, edited 16 times in total.
Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: MrCrowley » Sun Mar 07, 2010 6:00 pm

It's a shame no one has replied but I found the first link pretty interesting, learned a few things. I'd say it's a must read for anyone wanting to take pneumatics a step further than a basic sprinkler valve cannon.
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: jackssmirkingrevenge » Sun Mar 07, 2010 6:06 pm

Same here, always wondered what those symbols meant :roll: :D
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: MrCrowley » Sun Mar 07, 2010 6:13 pm

Here's a list with even more symbols and a tool to draw valves with the symbols:
http://www.smc.co.nz/pages/pneumatic_design.html
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: jackssmirkingrevenge » Sun Mar 07, 2010 6:18 pm

<-------- duly noted :D
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: Patto » Sun Mar 07, 2010 7:39 pm

Very nice :lol: thank you
  • 0

User avatar
Patto
Sergeant
Sergeant
 
Posts: 96
Joined: Wed Jan 20, 2010 7:08 pm
Reputation: 0

Unread postAuthor: Slauma » Sun Mar 07, 2010 8:41 pm

One reason I think DCVs aren't more widely used is their lack of availability to many. I know McMaster has a selection, ebay has been hit or miss for me, and googling hasn't really yielded any good results. Do you know somewhere where you can order DCVs online?
  • 0


Slauma
Specialist
Specialist
 
Posts: 46
Joined: Sun Dec 20, 2009 12:28 pm
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: POLAND_SPUD » Sun Mar 07, 2010 9:16 pm

@Slauma
I'll write more about that later (I'll edit the first post). I realize that CDV are not something you can buy at Lowes or Homedepot. They are normally used in pnumatics, stuff that is used in automated plants and things like that

You can order DCV from many places:

1. directly from manufacturers (Clippard, Festo, Humprey, Bosch Rexroth, SMC to name just a few) or their distributors (in most cases you can order them online from their sites) or online shops selling pneumatic equipment

2. ebay (links directly to 'pneumatic valves' category)

option no 1 can be quite expensive so I guess that ebay is the best source of valves...

the only problem is that you have to visit it from time to time to find the best bargains and stuff you want, and that you have to understand some basic notions about DCVs (so that you can buy exactly the best valve for your particular application... so for example if all you need is a DCV for filling&venting a QEV gun you might be better off with a manually actuated valve than a solenoid valve... similarly one with a spring return would be better than a toggle valve)
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: iknowmy3tables » Fri Mar 12, 2010 5:30 pm

I think you should post this kind of info on the wiki or on the how to.
One thing I've wanted to do is organize this kind of info so newbies could quickly pick up on how to build semi automatic and fully automatic pneumatics, then maybe just maybe the nerf community would build some decent nerf guns
  • 0


iknowmy3tables
Major General
Major General
 
Posts: 1558
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Country: United States (us)
Reputation: 0

Unread postAuthor: POLAND_SPUD » Sat Mar 13, 2010 12:04 am

yeah i know I am still adding new stuff to this... I add a short how to on buying them too or maybe add some videos...
once that's done it can be sticked I guess
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: bobgengeskahn » Sat Mar 13, 2010 6:39 pm

yeah, I'd like to 2nd the stickie idea. I've had to read and dig for months to figure out a fraction of what is in this thread.
  • 0


bobgengeskahn
Sergeant
Sergeant
 
Posts: 84
Joined: Thu Jul 23, 2009 5:40 am
Reputation: 0

Unread postAuthor: Gun Freak » Sat Mar 13, 2010 9:02 pm

So basically (man I say that a lot :D ) a DCV can be used for filling and piloting a qev?
  • 0

OG Anti-Hybrid
One man's trash is a true Spudder's treasure!
Golf Ball Cannon "Superna"M16 BBMGPengunHammer Valve Airsoft SniperHigh Pressure .22 Coax
Holy Shat!
User avatar
Gun Freak
Lieutenant General
Lieutenant General
 
Posts: 4969
Joined: Mon Jan 25, 2010 4:38 pm
Location: Florida
Country: United States (us)
Reputation: 11

Unread postAuthor: POLAND_SPUD » Sat Mar 13, 2010 9:31 pm

yes, among other things...

if you wanted to do this with ball valves you'd need two valves - one for piloting and one for filling. You would have to open the first one to fill the gun, then close it and then open the other one to pilot the gun. With a dcv valve you can pilot and fill the gun with just one valve and it can be attached directly to the main valve, which lowers mass and pilot volume when compared with a setup with two separate valves)
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: ramses » Mon Mar 15, 2010 4:16 pm

POLAND_SPUD wrote:yes, among other things...

if you wanted to do this with ball valves you'd need two valves - one for piloting and one for filling. You would have to open the first one to fill the gun, then close it and then open the other one to pilot the gun. With a dcv valve you can pilot and fill the gun with just one valve and it can be attached directly to the main valve, which lowers mass and pilot volume when compared with a setup with two separate valves)


or a 3 way ball valve... but that might actually be considered a type of DCV.
  • 0

POLAND_SPUD wrote:even if there was no link I'd know it's a bot because of female name :D
User avatar
ramses
Major General
Major General
 
Posts: 1679
Joined: Thu May 29, 2008 6:50 pm
Reputation: 3

Unread postAuthor: POLAND_SPUD » Mon Mar 15, 2010 4:28 pm

well yes...

though ball valves are not ideal... to open a simple BV you need to turn the handle 90 deg. With a 3 way BV you need 180 deg turn...that's a lot IMO opinion..

now if you compare that with a push button valve with a spring return... well it feels much better and more like a trigger on real guns


ohh btw I updated the first post...

and I think I might have found a way that would allow to use some indirect acting valves at higher pressures.. but I've got to test it first
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Next

Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Yahoo [Bot]

Reputation System ©'